Temporary redirect port in N seconds, use iptables or nftable rule.
临时重定向端口， 使用 ipt 或 nft 规则。
In the two directories are the programs (written in C) corresponding to the IPT and NFT rules.
just execute gcc -O -o xxxx rdr_port_ipt to complite an executable file.
strip xxxx can make the executable file smaller.
两个目录中分别是对应 IPT 和 NFT 规则的 C语言程序。
只需执行 gcc -O -o xxxx rdr_port_ipt 即可生成可执行文件。
strip xxxx 可以让可执行文件更小一点。
Execute rdr_port_ipt or rdr_port_nft :
- Insert a port redirection rule into the iptables rule table or nftable chain according to the source IP provided.
- The program resides in the background and waits for N seconds (depending on the command line parameters).
- Remove the previously inserted redirection rule from the iptables or nftable.
- The program done & exit.
The compiled executable file can be set with suid (chmod 4555 ...), which is called and executed by web script and temporarily redirected the port.
For example 443 -> 22, You can use the SSH client connect to port 443 in a few seconds, and then even if the redirection rule is deleted, your SSH connection will not be affected. Until you logout.
For example, PHP:
// $ip=$_SERVER['REMOTE_ADDR'];
$ip='1.2.3.4';
exec('/somepath/rdr_port_ipt '.$ip.' 20 a b');
For example, py3:
import subprocess
# import flask
# sip=flask.request.remote_addr
sip='1.2.3.4'
output=subprocess.getoutput('/somepath/rdr_port_ipt ' + sip + ' 20 a b')
执行 rdr_port_ipt ：
- 根据 提供的来源 IP，在 iptables 规则表, 或nftable chain 中插入一条端口重定向规则。
- 程序驻留后台等待 N 秒(根据命令行参数)。
- 从 iptables 规则中 或nftable chain中 删除之前插入的重定向规则。
- 程序结束退出。
编译后的可执行文件，可以设置SUID (chmod 4555 ...)，由网页脚本调用，达到临时重定向端口的目的。
如 443 -> 22 , 你可以在几秒内用 SSH 客户端连接443口，然后，即使重定向规则被删除，也不影响你的 SSH 连接。直到你主动logout。
比如，php：
// $ip=$_SERVER['REMOTE_ADDR'];
$ip='1.2.3.4';
exec('/somepath/rdr_port_ipt '.$ip.' 20 a b');
如, py3:
import subprocess
# import flask
# sip=flask.request.remote_addr
sip='1.2.3.4'
output=subprocess.getoutput('/somepath/rdr_port_ipt ' + sip + ' 20 a b')
rdr_port_nft : see [ for_nftables/]
2020-03-10.
end.